I notice a lot of the program files have a debug section or function
Without writing a separate program is there a way to run the debug
portion from the command line . ie dmd -switch somedfile ?

dmd -debug somefile
or you can use -debug=level or -debug=ident for debugs whitch have a
level or an ident. see dmd --help

That only includes the debug code. "debug" is used as a conditional
compilation section. If a user want to call the code in the debug section,
that will, by design, requirer some more code.

A fairly unrelated switch/code-block which allows you to execute specific
sections of code with a flag is the "unittest" block and
associated -unittest flag to dmd.
Not sure if this would be any more applicable.